1. Field of the Invention
The present invention relates to a data storage tape drive system having a locking mechanism for locking the reel within the tape cartridge when the tape cartridge is not in a tape drive system.
2. Background Art
Data storage tape drive systems are used to store large volumes of information for subsequent retrieval and use. Data storage tape drive systems are used to store computer data, audio files, and video files.
Data storage tape drive systems generally include interchangeable data storage tape cartridges that are selectively loaded into a tape drive system to store or retrieve data. Data storage tape cartridges generally include a housing, a tape reel, and magnetic storage tape that is wound on the tape reel. Tape drive systems generally include one or more drive hubs that are configured to operatively engage the data storage tape cartridge and rotate the tape reel. The drive hub is driven by a drive motor in a controlled manner so that transducers such as magnetic read/write heads record or read data on the storage tape.
Some tape drive systems are designed to use single reel data storage tape cartridges that interact with the tape drive system by allowing tape to be fed from the cartridge to a reel that is part of the tape drive system and outside the data tape storage cartridge. Another type of tape cartridge uses a dual tape reel configuration. With either type of cartridge, it is preferred to lock the tape reels to the cartridge housing when the cartridge is not disposed in the tape drive system. To lock a tape reel within a cartridge, a brake assembly or lock may be provided for each tape reel. The brake body generally includes a first portion engaging the tape cartridge housing and a second portion engaging the tape reel. The cartridge engagement portion may be connected to the cartridge housing in a sliding relationship in which an inwardly extending tab is received in a slot. The tape reel engagement portion of the brake is selectively connected to the tape reel. The tape reel engagement portion has a plurality of teeth that are oriented to engage a corresponding set of teeth on the tape reel in a locked position. A spring is provided to bias the brake body into its locked position.
When the tape cartridge is placed in the tape drive system, the brake body is moved out of its locked position to allow the tape reel to rotate. The tape reel is normally rotated by a drive hub that shifts the brake body from its locked position to an unlocked position.
While the above system is widely accepted, improvements in tape drive technology enabling tape drive systems to operate at higher tape speed have necessitated higher drive chuck rotational rates. Potential problems arise when higher drive hub speeds are achieved. Higher hub rotation speeds may cause increased friction and heat stress on the brake body components.
Another proposed solution is disclosed in U.S. Pat. No. 6,452,747 that discloses a data storage tape cartridge that is better suited for high speed operation. The disclosed data storage tape cartridge includes a housing, a tape reel, a storage tape, a brake, and a spring. The brake body is disposed in the central bore of the tape reel and includes a stem, a reel engagement section, and a wear button. The stem is attached in a sliding relationship to a receiver associated with a first housing section. The reel engagement section is configured to selectively engage a portion of the tape reel in a locked position with the concentric ring of teeth facing in an axial direction. The wear button is engaged by the drive hub of the tape drive system to unlock the brake by shifting the brake body out of its locked position. The spring biases the brake body into its locked position causing the brake body to rigidly connect the tape reel to the housing. To reduce friction in this system, a bearing ball on the drive hub contacts and rotates with a surface, concave or otherwise, of the brake body. According to this arrangement, thermal and frictional forces are minimized at high tape speeds. A disadvantage of this system is that substantial travel is required to shift the brake body against the spring to release the teeth on the brake body from the teeth of the tape reel. The brake body must move more than the full depth of the engagement teeth to unlock the reel from the cartridge. Approximately 0.060 of an inch movement is required to lift the brake body off of the teeth and an additional 0.060 of an inch is required for centering the reel in the cartridge. With half height drives, even less space is available for locking and unlocking the brake mechanism and for centering the reel within the cartridge. In addition, half height drives normally have a reduced range of elevator travel.
Accordingly, a need exists for a data storage tape cartridge for a tape drive system that reduces the amount of travel required for unlocking and locking the reel. There is also a need for reducing the amount of movement required to center the reel for threading into the tape drive system for single reel data storage tape cartridges. By reducing the amount of travel required, the quality and reliability of the tape drive system and data storage tape cartridge can be increased. Less movement of the reel and brake within the cartridge will result in less alignment problems and fewer problems relating to drive run outs.